Stress Plates are designed for use with Deck Screws and Spike anchors. For Powerlite specially designed stress plates are listed in the applicable product sections. Stress plates are used when attaching insulation and single ply materials to distribute load and prevent the material being fastened from pulling over the head of the fastener. In addition to the stress plates, a sealing washer and a plastic bearing washer are available for use with flashing and termination systems.Insulation plates, are used when mechanically attaching rigid form insulation to roof decks.They are manufactured in 3" diameter for use with truss head No.12 Deck Screws, and 3/16" and 1/4" Spike anchors. Two carbon steel plates, Type 304 stainless steel plate and a plastic plate are available. A recessed plate, a Type 304 stainless steel plate and a plastic plate are available for use with the No.12 hex washer head Deck Screws.The design of the insulation plate allows it to flex during installation if a fastener is overdriven preventing fracturing of the insulation board and facer. Sharp edges which could protrude above the insulation surface are eliminated by the round design. For corrosion resistance, a Galvalume coating is applied to the carbon steel plates. This coating, comprised primarily of aluminum and zinc, provides a degree of corrosion resistance which allows the material to meet the corrosion resistance required by Factory Mutual Research Corporation Standard 4470.Membrane plates, sometimes called lap plates, are used when mechanically attaching single ply material in the area of the lap or seam. They are manufactured in a 2" diameter for use with No.12 Deck Screws and 3/16" and 1/4" Spike anchors. The 2" membrane plate is formed with four barbs to provide Positive engagement with the membrane to reduce the possibility of tearing the single ply material under load. For corrosion resistance, a Galvalumecoating as described above is applied to the plates.